Palmqvist test method for Ti-based cermets and WC-CO hardmetals
Experiments were performed to assess the measurement uncertainty in the Palmqvist method for toughness determination which is based on measuring the length of cracks generated at the corners of Vickers hardness indentations. It was found that although the use of an optical microscope separate from that on the hardness machine gave slightly longer total crack lengths and indentations, the difference was barely greater than the measurement uncertainty. The use of a field emission SEM gave high crack lengths, but low indentation diagonal measurements were obtained due to the difficulty in defining the corners of indentations in the SEM. When Palmqvist measurements were made on a range of cermets and hardmetals, it was found that the differences in the Palmqvist parameter from specimen to specimen in the materials examined were less than the experimental uncertainty measured in the early part of the study. Annealing the specimens resulted in the measurement of longer crack lengths and indentation diagonals, and gave a significant reduction in the values of Palmqvist parameters. (Copyright (c) Crown Copyright, 1991.)
- Research Organization:
- National Physical Lab., Teddington (United Kingdom). Div. of Materials Metrology
- OSTI ID:
- 5401715
- Report Number(s):
- PB-92-151760/XAB; NPL-DMM(A)--33
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
CARBIDES
CARBON COMPOUNDS
CERMETS
COMPOSITE MATERIALS
CRACK PROPAGATION
DATA COVARIANCES
FRACTURE PROPERTIES
MATERIALS
MECHANICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SURFACE TREATMENTS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN CARBIDES
TUNGSTEN COMPOUNDS
VICKERS HARDNESS